Pearl buttons or blanks



UNITED STATES PATENT OFFICE.

CHARLES B. DAVIS, 01 NEW YORK, N. Y.

METHOD OF TREATING PEARL BUTTONS 0R BLANKS.

No Drawing.

To all whom it may concern:

Be it known that I, CHARLES B. DAVIS, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of Treating Pearl Buttons or Blanks, of which the following is a specification.

This invention relates to a method of treating pearl buttons or the blanks or ma tcrial from which said buttons are made, for the particular purpose of bleaching or whitening the same, thereby to increase their desirability and value in trade.

Vhat is generally known as the bark, that is the back of the button or blank or shell is usually dark in color, and, showing through the transparent pearl face gives a corresponding tint. to the button which is undesirable because the standard perfect button is white. Of course this bark or backing might be, bodily removed but this course would have the disadvantage that the button or shell would be weakened. By my invention I propose to remove from this bark or backing the undesirable coloring, and to substitute for it pure white, with the result that the button will be white.

In the practice of my invention I dissolve out part of the calcium carbonate, which is intermixed with the albuminous matter of the bark (chiefly calcium albuminate), and then combine with this exposed albumin, some substance which will give the desired coloring to the finished article.

Assuming that the purpose is to whiten the button or blank I have found that this can 'be accomplished as follows. I prepare a solution by adding an equal bulk of water to crystallized nitrate of bismuth, which is heated to near the boiling point, whereupon nitric acid is added, drop by drop, until a clear solution results. The rough blanks are immersed in this solution in the cold, or

Specification of Letters Patent.

Patented Aug. 12, 1919.

Application filed October 29, 1917. Serial No. 199,023.

the finished buttons are embedded face down in paraflin with the bark exposed and the solution flooded on the bark. The action of the solution is allowed to continue until eifervescence ceases, (usuall about one minute),

when the bark will be ound to have become bleached and whitened. The articles are now removed from the solution and washed free from acid in cold water. If they are kept in the water over night they become extremely white, from the complete deposition of the bismuth salt. They are next dried and may be polished or otherwise fin-- ished as desired. It will be understood that the nitric acid in solution removes the calcium carbonate from the albumin, while the bismuth deposits, both as the sub-nitrate and as an albuminate.

It will be understood that other acids than nitric acid may be employed to keep the bismuth in solution, as for instance, sulfuric or hydrochloric; or organic acids such as tartaric or citric may be used. Likewise, other metals may be substituted for the bismuth. For instance, butter'of antimony will eifect a similar result by depositing on the mere addition of water. This invention contemplates the removel from the bark of the calcium carbonate and the deposition in place of the removed material of some material having the desired coloring.

I claim:

The method of treating pearl buttons or blanks to change the coloring thereof, which consists in treating the blanks or buttons with a solution comprising water and cryse tallized nitrate of bismuth, to which has been added nitric acid until a clear solution results, then after the calcium carbonate of the bark has been removed by the nitric acid and replaced by the bismuth, washing the buttons free from acid and drying.

In testimony whereof I aflix my signature.

CHARLES B. DAVIS.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, 1!. 0. 

